Electric-arc lamp



(N0 Mode 1.)

E. THOMSON. ELECTRIC ARC LAMP.

No. 444,925. P44411444 Jan. 20, 1891.

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UNITED STATES PATENT OFFICE.

JLIHU THOMSON, OF LYNN, MASSACHUSETTS, ASSIGNOR TO THE THOMSON- HOUSTON ELECTRIC COMPANY, OF CONNECTICUT.

ELECTRIC-ARC LAM P.

SPECIFICATION forming part of Letters Patent No. 444,925, dated January 20, 1891.

Application filed November 22, 1884. Serial No. lath-622. We model.)

To aZZ whom it may concern.-

Be it known that I, ELIHU THOMSON, a citizen of the United States, and a resident of Lynn, in the county of Essex and State of Massachusetts, have invented certain new and useful Improvements in Electric Arc Lamps, of which the following is a specification.

The present invention relates to mechanism for regulating the separating and feed movements of the electrodes in electric-arc lamps fed from a circuit having a constant or nearly constant current.

The object of the invention is to save ener gy in the operation of such lamps and to cause the lamp to produce an adjustment of arc with delicacy and ease.

The principle of my invention may be thus stated. Instead of causing, as in usual practice, a direetcircnit magnet or magnet in the line-circuit to act oppositely to a derivedcircuit magnet about the are itself, I use such magnets in such waythat they are in a measure independent, and while in the former and older arrangement the available force neces sary for the adjustment of the carbons is the difference of force exerted by the magnets in opposition to each other, in my present inven tion the derived-circuit magnet is opposed by a spring, and the force in playin adjusting the carbons is sometimes that of the directcircuit magnet alone, and sometimes it is the surplus of force which the derived-circuit magnet exerts over the restraining force of its opposing spring. By my arrangement the 3 5 actual power of the direct-magnet needed is quite slight, being only that which is just sufiicient i0 separatethe carbons, the magnets not having to oppose the increasing force of the derived-circuit magnet as the carbons separate. Consequently I am enabled to reduce the energy of current to a fraction of that expended in the so-called differential systems, where the two magnets are made to oppose one anothers actions directly. The advantage will be manifest in the energy of circuit available and useful for light.

In the accompanying drawings, Fi ure 1 is a side elevation of a lamp embodying my invention. Fig. 2 is a perspective View of the working parts in a lamp of slightly-modified construction. Fig. 3 is a diagram of connections, illustrating the manner in which the magnets are connected to the circuit. Fig. t shows a modification in which the magnets armature levers are pivoted on different cen ters.

D indicates an electromagnet, which is in the dir ct circuit from X to the positive carbon rod or holder R, (being connected in any usual or desired manner,) the carbon E E, and to Y. Its position in the general circuit is shown diagrammatically in Fig. 3. Its ar mature N is carried by a lever L, pivoted at p in the frame of the lamp in any suitable manner and carrying or supporting any usual or desired form of clutch or clamp or other feed mechanism, such that the carbon-rod may be lifted on movement of the mechanism in one direction and may be released and permitted to feed on movement in the other direct-ion. A feed mechanism of this description is here typified by a clutch C, such as I have de scribed and shown in various of my prior patents. The magnet 1) acts through its armature, when it is energized, to lift the clutch or clamp and the rod R, so as to separate the carbons. A daslrpot J checks sudden movements of the lever L L. The winding of the magnet D is such that with the normal current it is nearly equilibrated-that is, will So have just suflicient power to lift the rod R and form an are, but no more. It is also preferably of such form or construction, or a re tractor is so applied, that its power to raise the rod shall be nearly uniform in all positions of its armature. This end may be socured by giving the pole of the magnet a co noida-l or conical form, as indicated, and perforating the armature, so that the pole shall extend through the perforation, thus giving a go nearly-uniform attraction in all positions of the armature. Other forms might be used. Under the conditions stated a very small force applied to L L to make it lower the clutch will cause a feed of the upperor positive car- 5 bon. This force is applied at the proper time when an are slightly extended beyond a normal length is formed at E by the agency of a derived-circuit magnet K, acting upon its rmature N, which magnet only then has an excess of force over and above that of a powerful opposing spring S, which is up plied to thearmature-lever L of electro-magnet K, and can be stretched so as to permit lever L to move only when the magnet K gets an increased force from the widening or opening of the arc beyond the normal extentat which the lamp is designed to burn. The lever L is mounted upon a fulcrum at p, in common with lever L, but is so mounted in any desired way as to move independently of the lever L and freely. It is provided with an arm or stud a, by which it may bearupon and depress the lever L when the magnet K acquires the requisite power for moving the lever against the retractor S. The magnet K is in a derived circuit around theca'rbons,as indicated in Fig. 3, one of its terminals being connected to the main circuit between the magnet D and the arc in any desired manner--as, for instance, by connection to the frame of the lampwhile its other terminal is connected to the conductor leading to Y. The magnet K or its armature is also preferably so constructed that with the same strength of current in the coils the magnet will exert the same pull upon the armature in all positions of the latter. The lever L, upon theapproach of the armature N to K upon the latters increased power over and above that exerted to prevent such approach by the spring S, just gives the slight force necessary to depress the lever L L so as to cause a feed of the rod R. As stated before, the power of magnet D is so adjusted that it shall just be able to lift the rod B, so that a very few grains of pressure exerted by lever L will depress it.

The operation is as follows: The carbons are together at the start, and the current, entering at X, goes through D, through E E, and out at Y, a part, after passing D, branching through K, which is .connected independently from It to Y. The magnet .D having lifted B so as to form an are, said are continues to burn and finally burns open until the magnet K is sufficiently energized to overcome the retractor S and so bring the lever L to a bearing at a. upon the lever L Lto release the clutch and feed the carbon. The action with proper clutch mechanism is delicate anda slow feed of the carbon takes-place. Should an-overfeed of the carbon take place, the resistance of the arc diminishes, so that the force of the retractor S completely overcomes the weakened attraction of K, entirely removing the armature N and lever L L from any restraining influence on D. Hence the full power of D is free to be exerted to form the new arc. hen the current is off the lamp, both armatures are withdrawn from the magnets, the lever L and clutch O and dash-pot J falling away, and the lever L and armature N being pulled away by S.

In the modification shown in Fi 2 the magnets are double solenoids with double cores N N. D is on the direct circuit of the line and K in the derived circuit about the arc. The levers L are independently pivoted to .the frame 13.

The clutch C is carried by the leverL, moved by armature N, and the lug at a catches upon a projection from N, whenthe power of themagnet K just overcomes the restraining action of the spring S, acting uponN toraise it. are as before. It is best in all cases that the magnets D and K have such nearly-uniform pull or attraction as is secured in solenoids or in the special forms of magnet shown in the figures.

Fig. 4 shows how the levers L L may be separately pivoted at p 1), so as to only act together when the contact at a is effected under the conditions previously stated.

The lamp is specially designed for use on The adjustments constant-current lines, where the force of D is constant at all times during operation.

hat I claim as my invention is-'- 1. The combination, in an-electric-arclamp, of a carbon or carbon-carrier, a feed-adjust ing mechanism engaging therewith and carried upon a suitable movable support, by which said mechanism and the carbon are sustained, a main-circuit magnet acting on said support with a power substantially'constant and adjusted with relation to the retractive influence, so that the magnet may just lift or cause separation of the-carbons, a derived-circuit magnet having an armature subjected to a retractive influence independent of first-named magnet, a retractorand a movable support for the armature of the derived-circuit magnet independent of that of the main-circuit magnet and arranged, as described, to operate upon the support for the carbon feed mechanism in a direction to lower the same only when moved away from its extreme retractive position, the retractive influence for the armatureof said derived-cir- .cuit magnet being adjusted, as described, so that said derived-circuit magnet maytact in opposition to the main-circuit magnet only when a normal arc is exceeded.

2. The combination, in an electric-arclamp, of a main-circuit magnet, through which the whole or substantially the whole current flowing to the arc passes, acarbon-supporting and feed-releasing mechanismmounted upon the armature-lever of said magnet, a derived-circuit magnet having an independently-mounted armature-lever normally disengaged from but adapted to engage with the support carrying the feed mechanism and to .act upon the same in magnetic opposition to the maincircuit magnet, and a retractor for thearmature-lever of said derived-circuit magnet,-adjusted as described to hold the armature-lever outof engagement with thesupport carrying the feed mechanism until the arc increases beyond normal length.

The combination, in an electric-arc lamp, of a support for the carbon-feed mechanism, a main-circuit magnet continually traversed byall or substantially all of the current flowingthroug-h the carbons, exerting a magnetic pull upon said support in one direction, a de IO to hold the same out of positiongvhere it will I engage with the support for the feed mechanism until the are shail increase beyond its normal or adjusted length. v

Signed at Lynn, in the county of Essex and State of Massachusetts, this 17th day of No- I 5 vember, A. D. 1884.

ELIHU THOMSON. Witnesses:

E. J. RICHARDS, W. O. WAKEFIELD. 

